Oooh, I'm nowhere near the magical third trimester but I'm having the same problem at the moment...my right nipple started itching like crazy yesterday! And today the left one is itchy too!

I've noticed that they look quite dry so that's probably what's causing the itch. I'm going to try some moisturiser and see if that does the trick. It's not a good look sticking my hand down my top every 5 mins and scratching like crazy!